mean96z28

I've been driving my 1996 z28 6-speed for a little over 4 months now and just the other day, I decided to do my second oil change on the car. The oil was only 2,000 miles old but was still extremely dark so I put a 1/4 of a quart of this engine flush in with 4.75 quarts of oil and right off the bat, my car wouldn't start. It would just crank and crank but not turn over.

So we waited maybe 5-10 minutes and it finally turned over but it started with hesitation... Like it didn't want to but then it finally did so we let it run fifteen minutes to let the engine flush do a little bit of it's work and then I shut the car off and drained the oil (which was still black) and let some new oil run through it until the oil was finally clear again and then put 5 quarts of the high milage in.

So then I go to start it and it started but it started to back fire extremely bad and then with the last shotgun sound, my car killed itself. So I tried to start it and it started RIGHT up with no hesitation or anything and it ran like it was brand new.

I let it run for 30 minutes at idle and it seemed perfectly fine so I shut it off and when I was on my way home (3 hours later) the car started to try and kill itself again and again.

So when I got home I tried to show my dad what was happening and when I parked the car, it killed itself and when I brought my dad out the car started right up and ran perfectly fine, even at 5,000 RPMs.

So then we shut off the car and didn't touch it at all and then the next day, I woke up for school and when I tried starting my car, it only cranked for about 15 minutes until I finally realized it wasn't going to turn over and so I looked for a ride to school.

It's hard to explain what it's doing but it seems as if it's loosing fuel pressure every now and then but my fuel pump is working and I have a full tank of gas.

My dad said that it might be from the engine flush knocking all that stuff loose and it might of clogged my oil pick-up tube and that would cause me to loose oil pressure and making my fuel pump kick off, causing the car to die. Any other suggestions?

The car is stock for the most part, just a cat-back exhaust, intake, SPEC stage 3 clutch, aluminum lightweight flywheel, new FPR, spark plugs, wires, opti, cap, rotor, control module, ignition coil, hoses, serpatine belt, and water pump have all been replaced.

Also when we were outside yesterday, waiting for it to die, it finally died and I kept hearing a spark sound... Like when something shorts out and sparks go everywhere but sparks weren't visable.

Please help because this is a daily driving car and my only car and it's been a real hassel not being able to drive!

Injuneer

The 96 F-Body LT1 does not have the oil pressure switch linked to the fuel pump. Its unlikley that changing the oil contributed to the problem.

Did you scan it? Could be an intermittent problem with the Opti wiring harness connector. Check it for corrosion or pin damage. OBD-II code scanners are available for less than $50.

Try and start it in the dark, and look for sparks on the coil, and on the plug wires.

Check the fuel pressure. Test gauge is cheap too.

You mention "high mileage".... how many miles on the engine?

What, if any, mods on the engine? What, if any, parts have been replaced, and when?

mrmint69

If the car wouldn't start after just adding the engine flush and having never run it then it wouldn't have caused any issues your describing. Did you do anything else even if it seems irrelevant during the oil change? You should get a fuel pressure gauge and see if its possibly your problem. Even if the pump comes on and you hear it running doesn't mean you have proper pressure. This will also tell if you new fpr is working correctly. What is the last thing you did and how long ago?

Mtxz453

yea the engine flush wouldn't really have anything to do with it. Check your intake elbow, i was working on my car this summer and accidentally knocked off the intake elbow a little and didn't know it. It would run then stutter and shut off and then wouldn't start at all. When unregistered air is getting into the engine it will have to much air and not enough gas.

Also check to see if the icm is loose or not working. Also make sure all your wires are intact and connected properly.

mean96z28

Yeah, so yesterday I started the car and it started up with hesitation again but I did, however, notice that when I reved it and it came down on RPMs, water shot out of my exhaust. I reved it up to 3,000 RPMs 4 times and there was a puddle of water, roughly, 2 feet wide and 4 to 5 feet long. Could this be my problem? (Water in the gas tank)

Also, what it done to the motor is an intake and the PCM has a REALLY bad tune on it (bought the car like that without knowing).

When I first bought the car, back in december, it wouldn't run after I drove it two blocks so I ended up replacing the following:

-Cap
-Rotor
-Water pump
-Plugs
-Plug wires
-Control module
-Ignition coil
-Opti-spark distributor
-Allof my hoses
-Serpantine belt
-Fuel filter
-Fuel Injection Cleaner has been ran on my car
-Fuel pressure regulator

All of these were replaced and the F.I.C. was ran about two through three months ago.

But the new question, now, is : Will water in the gas tank cause my car to act the way it has been acting?

Also, I have an OBD II Scanner and I ran it on my car and there was only one code and it was just my O2 censor.

Fuel pressure gauge, however, I don't have... Should I buy one and see if fuel pressure is my problem? How much do these normally cost and where can I find them at?

mean96z28

Also, there are a little over 112,000 miles on the car so high milage should be the right type of oil for the car, I would assume. The weight of the oil is 10/30

Injuneer

Had the car been left idling a lot recently? When you burn fuel, it forms water and CO2. Its normal for water to build up in the exhaust at cold idle. The amount you describe seems excessive, though. Have you checked it for a head gasket leak?

Contaminated fuel will cause significant problems. Its not likely to cause a major increase in water in the exhaust, since the exhaust already has a lot of water in it.

What was the code for the O2 sensor? If the A/F ratio is screwed up because of a faulty sensor, it could cause it to run rich, and increase the amount of water in the exhaust. Don't minimize the problem by saying "just an O2 sensor"..... that's one of the most critical components of the engine control system.

mean96z28

Well for starters, no the car has not been left idling for awhile and when I cold started it yesterday, it was the first time I have started it in the past 12 hours and the O2 sensor has been bad ever since I bought the car and I think I have all of the O2 sensors burnt out except for the rear right one because I replaced that one about a month ago.

mean96z28

So does anyone have any idea what this could possibly be? I really need help with this because, like I said, this is a daily driven vehicle and with my car not running, I'm consistantly late to school, work, etc.

mrmint69

If it was me i would buy 2 new Ac Delco O2 sensors and install them and see how the car runs. It wouldn't hurt to unplug the pcm battery for 30 seconds so it will start with a new set of long term fuel trims. I would think you either have gas, water or coolant coming out and if it does it just this once then you might be ok but if it continues you better figure what what causes it. Most auto parts stores sell the fuel pressure gauges for $25 or so and even if you don't suspect fuel problems it very nice to have.

mean96z28

Thank you Mr.Mint69 and Injuneer for your responses.

I will try buying a fuel pressure test gauge and see where that gets me but yes, it's defiantly water coming out of the exhaust tips.